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A.11 The JSP page Directive: Structuring Generated Servlets

Example of Using setContentType

ApplesAndOranges.jsp

Comparing Apples and Oranges

<%

String format = request.getParameter("format");

if ((format != null) && (format.equals("excel"))) {

  response.setContentType("application/vnd.ms excel");

%>

  
Apples Oranges
  
First Quarter 2307 4706
  
Second Quarter 2982 5104
  
Third Quarter 3011 5220
  
Fourth Quarter 3055 5287

The isThreadSafe Attribute

<%@ page isThreadSafe="true" %> <%!   Default   %>

<%@ page isThreadSafe="false" %>

  A value of

true

 means that you have made your code threadsafe and

that the system can send multiple concurrent requests. A value of

false

 means that the servlet resulting from JSP document will

implement

SingleThreadModel

 (see Section 2.6).

  Non threadsafe code:

<%! private int idNum = 0; %>

<% String userID = "userID" + idNum;

out.println("Your ID is " + userID + ".");

idNum = idNum + 1; %>

  Threadsafe code:

<%! private int idNum = 0; %>

<% synchronized(this) {

String userID = "userID" + idNum;

out.println("Your ID is " + userID + ".");

idNum = idNum + 1;

} %>

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